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Home , Birmanites, Chasmataspidida, Dolichopterus, Eurypterus, Metastoma, Pterygotidae

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Gondwana Research 23 (2013) 354–366

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Gondwana Research

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A new (Arthropoda: ) from southeast Turkey: Evidence for a cryptic Ordovician record of Eurypterida

James C. Lamsdell a,⁎, İzzet Hoşgör b, Paul A. Selden a,c,d a Paleontological Institute and Department of Geology, University of Kansas, Lawrence, Kansas, b TransAtlantic Petroleum Ltd.-Viking Int. Ltd. TR-06680, Ankara, Turkey c Natural History Museum, London, United Kingdom d Capital Normal University, Beijing, PR China article info abstract

Article history: A new of eurypterid, Paraeurypterus anatoliensis gen. et sp. nov., is described from the Upper Received 27 January 2012 Ordovician (Katian) Şort Tepe Formation of southeast Turkey. The single specimen, preserving the carapace, Received in revised form 20 April 2012 and fragments of appendages, appears morphologically intermediate between the eurypteroid Accepted 20 April 2012 families Dolichopteridae and Eurypteridae. P. anatoliensis retains the plesiomorphic conditions of crescentic Available online 2 May 2012 eyes with enlarged palpebral lobes and a quadrate carapace with ornamentation consisting of small pustules Handling Editor: J.G. Meert but also displaying the derived characteristics of genal facets and a row of large acicular scales across the posterior of each tergite. Phylogenetic analysis incorporating each of the major eurypterine clades and Keywords: all Eurypterina having a three-segmented genital operculum (the triploperculate condition) resolves Katian eurypteroids to be an unnatural group, with Dolichopteridae and Eurypteridae forming part of a grade Eurypterina leading to diploperculate Eurypterina. P. anatoliensis is intermediate between the two eurypteroid families, Paraeurypterus as is ‘’ minor from the Pentland Hills of , which is shown to be a distinct and Ghost ranges assigned to Pentlandopterus gen. nov. Using the phylogenetic topology to infer ghost ranges for each of the Phylogeny major eurypterid clades reveals that the majority of eurypterid superfamilies must have originated by the Katian, indicating a largely unsampled record of Ordovician . The occurrence of poor dispersers such as Paraeurypterus in the Ordovician of Gondwana is puzzling, and it has been suggested that they dispersed to the continent during periods of sea level lowstand in the Sandbian and Hirnantian, however this does not explain the lack of Ordovician species in and , given the well-sampled nature of these continents, and an alternative is proposed whereby eurypterids originated in Gondwana and radiated out to and in the late Ordovician and early , thus explaining their sudden appearance in the European and North American rock record. Published by Elsevier B.V. on behalf of International Association for Gondwana Research.

1. Introduction held view that the observed distributions represent a true signal, with eurypterids originating in Laurentia and being limited to dispersal Eurypterids are a monophyletic group of Palaeozoic aquatic along coastlines, with only the pterygotoids being able to cross open chelicerates with a distribution largely limited to the palaeo- (Tetlie, 2007a). Any new record of eurypterids from outside continents of , Armorica, Baltica, Iberia and Laurentia. Of North America and Europe is, therefore, of extreme interest, the 246 currently valid eurypterid species only 22 have been reported especially if they can be assigned to a group lacking the dispersal from outside these palaeocontinents; however, of these, only 13 can capabilities of the pterygotoids, and have a pre- age. be confidently assigned to a eurypterid clade (Table 1). While it has The majority of eurypterid occurrences outside North America and been suggested that the lack of eurypterids other than from Europe Europe consist of presumably poor dispersers (hibbertopteroids) and North America is a collecting and research bias (Plotnick, 1999), which occurred during the Carboniferous and , after and a number of further unnamed or fragmentary eurypterids have Gondwana has come into close proximity to Laurentia as a prelude been reported from outside of these continents (Braddy et al., 1995, to the amalgamation of Pangaea, or taxa with higher dispersal 2002; Braddy and Almond, 1999; Tetlie et al., 2004), it is the currently potential such as pterygotoids or carcinosomatids. Adelophthalmus Jordan in Jordan and von Meyer, 1854, another widespread genus, is ⁎ Corresponding author. also known from Gondwanan localities from the onwards E-mail address: [email protected] (J.C. Lamsdell). and it is likely that it was able to cross the already narrowing gulf

1342-937X/$ – see front matter. Published by Elsevier B.V. on behalf of International Association for Gondwana Research. doi:10.1016/j.gr.2012.04.006 Author's personal copy

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Table 1 Chronological list of undoubted eurypterids from palaeocontinents other than Baltica, Laurentia, Avalonia, Iberia and Armorica. Stylonurus (?) menneri and Borchgrevinkium taimyrensis from the early Devonian of Siberia (Novojilov, 1959) and Melbournopterus crossotus from the Silurian of (Caster and Kjellesvig-Waering, 1953) are not eurypterids and so have not been included. Eurypterus loi, Eurypterus styliformis and Eurypterus yangi from the Silurian of China (Chang, 1957) are probably based on undiagnostic material and have been excluded pending reevalution of the original material, as have Nanahughmilleria schiraensis and Parahughmilleria matarakensis from the Devonian of Siberia (Pirozhnikov, 1957), Adelophthalmus carbonarius (Chernyshev, 1933) from the Carboniferous of , and (?) australis from the Silurian of Australia (McCoy, 1899). Note however that reports of unnamed or undescribed eurypterids (Braddy et al., 1995, 2002; Braddy and Almond, 1999; Tetlie et al., 2004) are not listed here.

Eurypterids by period Author Age Region

Ordovician Onychopterella augusti Braddy et al., 1995 Hirnantian South Africa Silurian wangi Tetlie et al., 2007a Llandovery China Rhinocarcinosoma dosonensis Braddy et al., 2002 Ludlow–Pridoli Vietnam Slimonia boliviana Kjellesvig-Waering, 1973 Ludlow/Pridoli Bolivia Devonian cf. bohemicus Burrow et al., 2002 Pridoli Australia Adelophthalmus waterstoni Tetlie et al., 2004 Australia Pterygotus bolivianus Kjellesvig-Waering, 1964a / Bolivia Carboniferous Adelophthalmus irinae Shpinev, 2006 Tournaisian Siberia Cyrtoctenus wittebergensis Waterston et al., 1985 Tournaisian South Africa Megarachne servinei Hünicken, 1980 Gzhelian–Asselian Argentina Unionopterus anastasiae Chernyshev, 1948 Tournaisian–Visean Kazakhstan Permian Adelophthalmus chinensis Grabau, 1920 Asselian China Campylocephalus oculatus Kutorga, 1838 Guadalupian? Russia Hastimima whitei White, 1908 Sakmarian Brazil between Gondwana and Laurentia. One occurrence, however, appears unnamed, thick, limestones overlain by approximately to defy explanation: Onychopterella augusti Braddy et al., 1995, from 1000 m of the Giri Formation, comprising Silurian (actually Cambrian the Soom Shale of South Africa, which has been dated as latest and Ordovician) quartzites with subsidiary limestones and siltstones. Hirnantian to earliest Rhuddanian (Vandenbroucke et al., 2009). Some of the latter contained Cruziana trace and have been O. augusti does not appear to be a good disperser, as its posterior compared to analogous strata in northern Iraq (Dean and Monod, pair of appendages are not overly expanded into a swimming paddle, 1990; Dean, 2006). Between Hakkari and Çukurca the River Zap cuts a and its relatively basal phylogenetic position combined with its early deep valley to expose two inliers of Cambrian and Ordovician sediments, occurrence (before the major period of eurypterid radiation during mostly clastics, that form part of the Arabian Platform (Ghienne et al., the early Silurian) makes its appearance in Gondwana somewhat 2010). Dean et al. (1981) recognised that the Giri Formation was problematic. equivalent to the shales and sandstones of the Seydişehir Formation, Here, we report a second Gondwanan Ordovician eurypterid, described from the western Taurus Mountains but widespread in the Paraeurypterus anatoliensis gen. et sp. nov., a single specimen eastern Taurus, southeastern Turkey, and neighbouring parts of Iraq, from the Şort Tepe Formation (middle Katian) near Çukurca, and of Upper Cambrian and Lower Ordovician age. The strata southeast Turkey. The new species is placed in a phylogenetic disconformably overlying the formation, mainly comprising shales and context as intermediate between the families Dolichopteridae siltstones, were named the Şort Tepe Formation and considered to be and Eurypteridae and forms part of a basal grade of Eurypterina of Ashgillian age (Upper Ordovocian, late Katian–Hirnantian). In the leading to a clade defined by having only two fused plates in the Zap Valley, the thick Seydişehir Formation is unconformably overlain genital operculum. The phylogeny allows for ghost ranges to be by a Lower and Upper Palaeozoic succession that comprises the Upper estimated for each of the main eurypterid clades which indicate Ordovician Şort Tepe Formation, the Upper Devonian Yıgınlı Formation the existence of a diverse record of Ordovician eurypterids and and the Lower Carboniferous Köprülü Formation (Fig. 2A) (Higgs et al., the potential for discovery of further early Palaeozoic eurypterids 2002). It is in the Şort Tepe beds of this succession, on the northeast in Gondwana. side of the Zap Valley 7.5 km northwest of Çukurca (Fig. 2B), that the eurypterid specimen was discovered. The depositional environment of 2. Geological setting the Şort Tepe Formation is considered to be that of an outer shelf environment representing the culmination of a period of marine The Border Folds of southeast Turkey represent the northern part of transgression throughout the Seydişehir Formation which it the Arabian Plate dominated by the East Anatolian Fault where it unconformably overlies (Ghienne et al., 2010). contacts the Anatolian Plate (Fig. 1A), and consists largely of Mesozoic In the Hakkari–Çukurca area the Şort Tepe Formation is known and Cenozoic surface crops with subsurface Palaeozoic formations for its well-preserved faunas, with Dean and Zhou (1988) cropping out in places (e.g. at the Derik, Mardin, Şort Tepe, and Zap reporting the genera Lonchodomas Angelin, 1854, Dindymene areas) that represent an almost complete Cambrian–Ordovician Hawle and Corda, 1847, Prionocheilus Rouault, 1847, Calymenesun succession (Fig. 1B). The eurypterid specimen was discovered during a Kobayashi, 1951 and Birmanites Sheng, 1934, along with fragments geological survey of the most southeastern regions of Anatolia, near of diplograptid graptolites and the brachiopod Aegiromena Havlíček, the border with Iraq. Here, the early Palaeozoic strata encompass the 1961, all located in the grey shale beds within the formation, the Derik and the Habur groups which extend from the Amanos-Pazarcık same lithology from which the eurypterid was discovered. These area in the west to Hakkari-Çukurca in the east (Cater and Tunbridge, macrofossils were used, through comparison with similar faunas 1992; Bozdoğan and Ertuğ, 1997) and palaeogeographically belong to elsewhere, to infer a pre-Hirnantian Ashgill age for the formation. the northern margin of the Arabian Plate of Gondwana throughout Palynological investigations on Ordovician deposits from Turkey are the Palaeozoic. fairly rare and deal principally with the less mature organic-walled Lower Palaeozoic strata were first recognised in southeastern Turkey microfossils recorded in the Border Folds area where rich and about 30 km southwest of Hakkari by Altınlı (1963) who reported well preserved Upper Ordovician acritarchs, sporomorphs, and Author's personal copy

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Fig. 1. A, map showing the region surrounding the border between the Arabian and Anatolian plates. Early Palaeozoic outcrops are shown in black. The Zap Valley is located between Hakkari and Çukurca; B, diagram showing the lateral extent of the early Palaeozoic formations between Antakya and Hakkari on the Arabian plate. After Bozdoğan and Ertuğ, 1997. chitinozoans have been reported from the Habur Group (Steemans et Mk II digital camera with a Canon macro MP-E 65 mm 1:2.8 lens al., 1996). More recently, Paris et al. (2007a, 2007b) have determined with a polarizing filter and a polarized light source with the specimen chitinozoan assemblages in the upper parts of the Şort Tepe submerged in alcohol. Image processing was carried out using Adobe Formation dated to the late Caradoc (middle Katian), thus making Photoshop CS4, and interpretive drawings were prepared for the new eurypterid older than Orcanopterus manitoulinensis Stott et publication using Adobe Illustrator CS4, on a MacBook Pro running al., 2005 and Megalograptus ohioensis Caster and Kjellesvig-Waering OS X. in Størmer, 1955 (both from the late Katian of Laurentia) and The specimen consists of parts of the prosoma and mesosoma Onychopterella augusti (from the Hirnantian of Gondwana), but preserved in a pale grey siltstone with red-brown coloured cuticle younger than the stylonurine Brachyopterus stubblefieldi Størmer, preserved in places (Fig. 3), such as on the carapace dorsal surface 1951 (from the Sandbian of Avalonia). anterior to the left lateral eye, where it shows a concentric, pustular ornament. Part of the carapace posterior is broken away, revealing 3. Materials and methods the prosoma– junction and the usually hidden, poorly sclerotized, true first tergite. Anteriorly on the right side, the carapace The specimen was recovered from the Upper Ordovician Şort Tepe is broken away to reveal the ventral plate (doublure). The median Formation of southeast Turkey and is deposited in the Natural History suture of the doublure is not visible, but there is clearly no epistomal Museum of Maden Tetkik ve Arama Genel Müdürlüğü, Ankara plate or transverse suture. Lateral eyes are preserved, but median (MTANHMSETR). Material of Eurypterus minor (Laurie, 1899), studied ocelli seen only as pale, circular impressions, and the right one is for comparison, is held at the National Museums of Scotland (NMS), mostly obscured by a crack. Anterior to the right lateral eye, and Edinburgh, UK. Eurypterid terminology largely follows Tollerton posterior to the left lateral eye, are what appear to be worm burrows (1989) for morphology of the carapace, , lateral eyes, or grazing traces. prosomal appendages, genital appendage, opisthosomal differentia- To the right of the carapace, the remains of four appendages can tion, , and patterns of ornamentation; however, the terminology be seen. The most anterior (appendage III) consists of a single for the ventral plate morphologies follows the revised types of Tetlie podomere that is angled underneath the following appendage and et al. (2008). Selden (1981) is followed for prosomal structures thus lost from view. Appendage IV consists of a single visible and cuticular sculpture and the labelling of the appendages. Termi- podomere and a spine from the preceding podomere that is hidden nology for the segmentation of the genital operculum follows under the carapace. No details are available of appendage V apart Waterston (1979). The specimen was studied using a Leica M205C from its existence: it appears from beneath the carapace but is then stereomicroscope and photographs were taken on a Canon EOS 5D covered by the overlying, forward-thrust appendage VI. Author's personal copy

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Fig. 2. A, generalized columnar section of the Upper Cambrian-Lower Carboniferous rock units of the Zap Valley section (after Ghienne et al., 2010) with the location of the eurypterid shown within the Şort Tepe Formation; B, location and geological maps of the Zap Valley and Şort Tepe section.

In the mesosoma, seven fully expressed tergites and the first, Eurypterina, all the taxa from the analysis of Tetlie and Cuggy (2007) usually hidden, true tergite are preserved which, though poorly were included, along with taxa from the analysis of Lamsdell (2011). preserved, can be seen on both lateral margins. On the right side of In to test the ramifications of the ghost ranges for each of the the specimen, the opercular plates can be seen projecting from major Eurypterina clades, representatives from each of the more beneath the tergites. The exact number of large, acicular scales on derived groups were also included, each represented by multiple each tergite is difficult to ascertain due to damage around exemplars which more accurately represent the character states and the posterior margins; however, it is clear that each tergite bore transitions of the group than a single exemplar, such as a single species three sets of large scales for a total of six to nine scales on each or a composite (see Brusatte, 2010). Mixopterus kiaeri Størmer, segment. 1934a and Carcinosoma newlini (Claypole, 1890a) were included to For the phylogenetic analysis, a matrix of 81 characters and 45 taxa represent the mixopteroids, Adelophthalmus sievertsi (Størmer, 1969) was compiled, which can be found in the Appendix along with and Nanahughmilleria norvegica (Kiær, 1911) for the adelophthalmoids, character descriptions. The synziphosurine opitzi and Hughmilleria socialis Sarle, 1903 and Pterygotus anglicus Agassiz, Richter and Richter, 1929 was specified as the outgroup following 1844 for the pterygotoids. Two other problematic Ordovician taxa Lamsdell et al. (2010a, 2010b) as it supposedly represents the most were also included: Megalograptus ohioensis and Orcanopterus plesiomorphic known xiphosuran (Anderson and Selden, 1997) manitoulinensis. O. manitoulinensis was considered by Tetlie (2007a) which are sister group to Eurypterida (Selden and Dunlop, 1998); and Tetlie and Poschmann (2008) to be part of an unnamed clade however, given the unclear nature of synziphosurine intra- consisting of Orcanopterus Stott et al., 2005, Waeringopterus Leutze, relationships (see Lamsdell, 2011) the chasmataspidids Chasmataspis 1961 and Grossopterus Størmer, 1934b which forms the sister-group laurencii Caster and Brooks, 1956, Loganamaraspis dunlopi Tetlie and to adelophthalmoids and pterygotoids, while M. ohioensis has Braddy, 2004, Diploaspis casteri Størmer, 1972 and Octoberaspis traditionally been considered a member of the Mixopteroidea (Caster ushakovi Dunlop, 2002 are included due to the shared synapomorphies and Kjellesvig-Waering, 1964), although Tetlie (2007a) considered it of a metastoma and genital appendage. These, however, were left as to be a basal taxon positioned between Onychopterella Størmer, 1951 ingroup taxa to test whether chasmataspidids fall outside Eurypterida and Eurypteroidea. or are a clade within Eurypterina, as suggested by Shultz (2007). In The analysis was performed using TNT (Goloboff et al., 2008; order to test the placement of the Turkish specimen among the basal made available with the sponsorship of the Willi Hennig Society) Author's personal copy

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Fig. 3. Paraeurypterus anatoliensis gen. et sp. nov. MTANHMSETR 10-İZ-01-1. A, Photograph of and only known specimen; B, Interpretive drawing of holotype. Shaded areas represent preservation of original cuticle. Label abbreviations: A, acicular scales; C, carapace; G, grooves; LE, lateral eye; MR, marginal rim; O, ocelli; OP, opercular plate; PL, palpebral lobe; S, spine; TA; tergite articulation; TT1, true tergite 1; VP, ventral plate; 1–7, tergites; III–VI, prosomal appendages; VI-4–VI-6, podomeres of prosomal appendage VI. Scale bars equal 10 mm. employing random addition sequences followed by branch swapping plates were functionally fused had also been recognised by Laurie (the mult command in TNT) with 100,000 repetitions with all (1893), Holm (1898) and Wills (1965) but appears to have been missed characters unordered and of equal weight. Jackknife (Farris et al., by subsequent authors. 1996)andBremersupport(Bremer, 1994)valueswerecalculated Suborder Eurypterina Burmeister, 1843 in TNT and the Consistency, Retention and Rescaled Consistency Grade ‘Eurypteroidea’ Indices were calculated in Mesquite 2.73 (Maddison and Maddison, 2010). Nonparametric bootstrapping is often difficult with mor- Remarks phological data due to the limited size of the dataset (Zander, Tetlie and Cuggy (2007) retrieved Eurypteroidea as a natural 2003) and so was not performed for this analysis. Jackknifing was group; however, the analysis herein resolves the group as paraphyletic performed using simple addition sequence and tree bisection- with a monophyletic Dolichopteridae sister-group to Eurypteridae and reconnection (TBR) branch swapping, with 100,000 repetitions the remaining Eurypterina (Mixopteroidea, Adelophthalmoidea and and 25% character deletion. The matrix and character listing can be Pterygotoidea). This result was somewhat foreshadowed by Tetlie and found in the electronic appendix has been deposited in the online Cuggy (2007), who remarked that the Eurypteridae were, in most MorphoBank database (O'Leary and Kaufman, 2007) under the respects, more derived morphologically than the Dolichopteridae and fi project code p568 and can be accessed from http://morphobank. appears to con rm the results from a less inclusive analysis per- org/permalink/?P568. formed by Lamsdell (2011). invalidates Eurypteroidea as a superfamily; however, the term is currently retained as an iden- fi 4. Systematic palaeontology ti cation for the grade of basal Eurypterina that it encompassed. In due course, this may be expanded to also encompass both the Moselopteridae and Onychopterellidae; but these are, for the moment, Phylum Arthropoda Latreille, 1829 retained in their own superfamilies. Chelicerata Heymons, 1901 Genus Paraeurypterus gen. nov. Superclass Sclerophorata Kamenz et al., 2011 species Order Eurypterida Burmeister, 1843 Paraeurypterus anatoliensis gen. et sp. nov. Diagnosis Etymology From the Greek παρά (similar) and Eurypterus due to its close Chelicerates with the opercula of somites VIII and IX fused into a similarities to the genus Eurypterus DeKay, 1825. genital opercular plate. Diagnosis Remarks ‘Eurypteroid’ with quadrate carapace possessing genal facets; After the identification of a metastoma and genital appendage in two small, crescentic lateral eyes with large palpebral lobe; carapace species of chasmataspidid (Dunlop, 2002; Tetlie and Braddy, 2004), ornamentation consists of small pustules, opisthosomal ornamentation Lamsdell (2011) determined the sole eurypterid autapomorphy to be consists of scales with a series of large acicular scales across the the possession of the fused opercula of somites VIII and IX forming the posterior region of the tergites. genital operculum. The fact that the median and posterior opercular Paraeurypterus anatoliensis gen. et sp. nov. (Figs. 3–4) Author's personal copy

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Holotype MTANHMSETR 10-İZ-01-1. Etymology Named after the Anatolian Peninsula where the specimen was found. Locality and age The only known specimen is derived from the Upper Ordovician (middle Katian) Şort Tepe Formation, southeast Turkey. Diagnosis As for genus. Description Preserved body length 84 mm; maximum width (at third tergite) 46 mm. Carapace maximum width 45 mm (at posterior), 32 mm long. Carapace anterior margin relatively straight, very slightly procurved medially; length:width ratio 0.70; genal angle 85°, therefore carapace subquadrate (Tollerton, 1989); posterior margin recurved, angling anteriorly for 2 mm. No epistomal plate or transverse suture (therefore Eurypterus-orErieopterus-type); plates ornamented with series of striate terrace lines (Fig. 4A), as seen in Eurypterus tetragonophthalmus Fischer, 1839 (Selden, 1981), Stoermeropterus conicus (Laurie, 1892) (Lamsdell, 2011), Parahughmilleria hefteri Størmer, 1973 and Erieopterus sp. (Poschmann and Tetlie, 2006). Lateral eyes centrilateral at most antero-lateral limit of quadrant (Tollerton, 1989); crescentic, associated with small palpebral lobe giving appearance of circular outline (Fig. 4B; the defunct ovocrescentic of Tollerton, 1989); 6 mm long, 3 mm wide (5 mm including palpebral lobe). Median ocelli central between posteriormost limit of lateral eyes; 1 mm×1 mm diameter. Carapace marginal rim narrow, extends across entire width of anterior and lateral margins, narrowing very slightly towards posterior, 1.5 mm at widest. Only small part of one podomere of appendage III preserved. Single preserved podomere of appendage IV 5.5 mm long, 3 mm wide, unornamented; spine from preceding podomere 3.48 mm long, 1.22 mm wide at base, ornamented with series of longitudinal striations; appendage of Hughmilleria-type. Only small part of one podomere of appendage V preserved. Visible portions of appendage VI consists of long, slightly curved podomere ornamented with slight scale projections or distally angled serrations on dorsal and ventral (probably podomere 4); longitudinal, parallel grooves run down length of podomere; 15 mm long, 7.5 mm wide; podomere 5 is 7 mm long, flaring distally from 6 mm to 7 mm wide. True first tergite 1 mm long. Opercular plates project from beneath tergites. First fully expressed tergite (from hereon just ‘first tergite’) shorter than following tergites; broadest point of body at third tergite (Table 2). Dorsal ornamentation consisting of continuous row of semilunate scales 1–1.5 mm from each tergite anterior border (Fig. 4C). Scale ridges indicate degree of overlap with preceding tergite; portion of tergite before ridge forms smooth articulating facet. Posterior to scale ridge are three discontinuous rows of semilunate scales before Fig. 4. Paraeurypterus anatoliensis gen. et sp. nov. MTANHMSETR 10-İZ-01-1. ornamentation becomes sparse, still consisting of isolated semilunate A, Magnification of exposed ventral plate, showing fine striate ‘terrace line’ ornament; scales. Row of acicular scales interspersed with much larger acicular B, Magnification of crescentic lateral eye with enlarged palpebral lobe; C, Magnification scales across posterior region of each tergite. Large scales, absent from of tergite ornament, showing the row of flattened scales at the posterior of the first tergite, increase in size from second to seventh tergite. Each tergite articulating facet and the large acicular scales towards the rear of the tergite. Scale bars equal 2 mm. with three sets of large scales (total 6–9scales),numberofscales possibly increasing with size of tergite. Remarks In general appearance, Paraeurypterus anatoliensis looks very are known from the carapace of a number of Eurypterus species, much like a species of Eurypterus, drawing initial comparison with including E. dekayi Hall, 1859 and E. tetragonophthalmus; however, Eurypterus tetragonophthalmus. A number of features, however, in all of these, the pustules are limited to the margins of the carapace show it to be distinct from that genus: the quadratic carapace, and anterior to the lateral eyes, and not covering the carapace, as which is trapezoidal in all Eurypterus species, the crescentic lateral appears to be the case in P. anatoliensis. The scale ornamentation of eyes with an enlarged palpebral lobe (a plesiomorphic state which the opisthosoma in P. anatoliensis also appears different to that of is lost in the Eurypteridae and the remaining derived Eurypterina), Eurypterus, possessing more large acicular scales than in any known and the carapace ornamentation consisting of small pustules. Pustules Eurypterus species, although the number of scales can vary between Author's personal copy

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Table 2 Diagnosis Proportions (length/width) of the holotype specimen MTANHMSETR 10-İZ-01-1 of Paraeurypterus anatoliensis. Eurypterina with a genital operculum consisting of two fused

12 34567 segments.

5/44 7/34a 7/46 8/45 8/42 8/40 8/31a Remarks

a Preserved dimensions. Diploperculata represents the clade of ‘derived Eurypterina’ as denoted by Tetlie and Cuggy (2007); those eurypterine groups to which ‘Eurypteroidea’ is sister-taxon, incorporating Mixopteroidea, them. While the species resembles Eurypterus, it possesses a number the unnamed ‘waeringopterid’ clade, Adelophthalmoidea and of plesiomorphic characteristics that have already been lost in Pterygotoidea. Two characters potentially define the clade: the first, Erieopterus Kjellesvig-Waering, 1958, the sister-taxon of Eurypterus, having a fused genital operculum composed of two segment (the and this is considered justification for its erection as a new genus, a diploperculate condition), gives the clade its name and is used to conclusion borne out by the phylogenetic analysis presented herein. define the limits of the infraorder. The form of the genital operculum Pentlandopterus gen. nov. is thought to be an important character, as the possession of a fused genital operculum may be the only eurypterid synapomorphy Type species (Lamsdell, 2011), with the Stylonurina and the basal Eurypterina Eurypterus minor (Laurie, 1899) (Moselopteridae, Onychopterellidae, Dolichopteridae, and Eurypteridae) Etymology sharing the plesiomorphic triploperculate (three segmented) condition (Tetlie and Braddy, 2004; Lamsdell, 2011). The other potential Named after the Pentland Hills, Scotland, from which the only characteristic of the clade is having a podomere VI-4 of equal length to known species is described. podomere VI-3 and VI-5, however Megalograptus (which is clearly Diagnosis diploperculate) has a VI-4 longer than VI-3 and VI-5 while the ‘Eurypteroid’ with a quadrate carapace possessing genal facets; dolichopterid Strobilopterus Ruedemann, 1934 also has all three cuticular ornamentation consisting of closely spaced pustules; lateral podomeres of equal length and so the character is not included in the eyes crescentic with large palpebral lobe. diagnosis of the clade. Pentlandopterus minor (Laurie, 1899) 1899 Eurypterus minor Laurie, pp. 587–588, plate V Figs. 27–29. 5. Comparison with other eurypterids 1899 Eurypterus minor Peach and Horne, pp. 594. 1912 Eurypterus minor Clarke and Ruedemann, pp. 132. Paraeurypterus is clearly differentiated from the supposedly more 1916 Eurypterus minor O'Connell, pp. 40. primitive suborder Stylonurina, based on the lack of a transverse suture 1955 Eurypterus minor Lamont, pp. 200. on the prosomal ventral plates and having prosomal appendage VI 1958 Eurypterus minor Kjellesvig-Waering, pp. 1123–1124. expanded into a swimming paddle. Although the distal podomeres 1999 Eurypterus minor Plotnick, pp. 120. of the paddle (including those that undergo the characteristic 2006 Eurypterus minor Tetlie, pp. 403–405, Fig. 4. broadening) are not preserved, the fourth, fifth and sixth podomeres fi 2007a ‘Eurypterus’ minor Tetlie, pp. 560. are. In eurypterids with a pediform prosomal appendage, the fth podomere is longer than the fourth, whereas those with a paddle Holotype have a fourth podomere that is longer or equal in length to the fifth. NMS G.1897.32.120 Paraeurypterus has a VI-4 that is longer than VI-5, and therefore has a swimming paddle. Furthermore, the fact that VI-4 is longer than VI-5 Additional material precludes it from comparison with the mixopteroid, adelophthalmoid NMS G.1897.32.166 (paratype), G.1897.32.129, G.1897.32.152, and pterygotoid clades, which all have a VI-4 equal in length to VI-5. G.1897.32.867. Paraeurypterus is therefore most comparable to Megalograptus Miller, Remarks 1874, Eurypteridae and Dolichopteridae (which with the exception of The species was given a modern redescription by Tetlie (2006), Strobilopterus all have VI-4 longer than VI-5). who considered it to be a Eurypterus. Tetlie and Cuggy (2007), Paraeurypterus, along with Pentlandopterus, shares several char- however, showed it to be phylogenetically distinct from Eurypterus acteristics with dolichopterids, including a dorsal carapace ornamen- but did not change the due to uncertainty as to the exact tation consisting of granular pustules, and crescentic lateral eyes position of the species. Our analysis confirms that Pentlandopterus associated with enlarged palpebral lobes; however, these are plesio- minor is not a Eurypterus and it is here assigned to its own genus. morphic conditions, also observed in onychopterellids, moselopterids While it shares many characteristics with Paraeurypterus anatoliensis, and Stylonurina. Both Paraeurypterus and Pentlandopterus lack the the difference in opisthosomal ornamentation clearly places P. synapomorphies of either dolichopterid clade, namely a short anatoliensis phylogenetically closer to the Eurypteridae and the two appendage VI that barely projects from beneath the carapace or an species are therefore assigned to different genera. articulating angle between VI-3 and VI-4 of less than 180°. Both Tetlie (2006) listed NMS G.1897.32.110 as a second paratype, but genera are separated from Eurypterus, however, in lacking a scale this specimen number is actually associated with a specimen of ornament on the carapace and having a quadratic rather than Drepanopterus pentlandicus Laurie, 1892. The accession number of trapezoid carapace. Eurypterus has also lost the plesiomorphic lateral the Pentlandopterus second paratype is at present unknown. eye condition, instead having an expanded visual surface with reduced palpebral lobe. One character that separates Paraeurypterus Infraorder Diploperculata nov. from Pentlandopterus, but suggests a closer affinity to Eurypterus and Included groups Megalograptus, is its possession of a row of large acicular scales across Mixopteroidea, Adelophthalmoidea, Pterygotoidea and the the posterior margin of each tergite. It is predominantly similarities ‘waeringopterid’ clade. in opisthosomal ornamentation, along with the morphology of ap- pendage V, that have led to comparison between Eurypterus and Etymology Megalograptus and so encountering a similar morphology in a new From the Greek διπλόω (double) and operculum. taxon may help indicate whether the similarities between the two Author's personal copy

J.C. Lamsdell et al. / Gondwana Research 23 (2013) 354–366 361 are synapomorphies, due to convergence or a result of retained the fact that Megalograptus shares several synapomorphies with plesiomorphic conditions. mixopteroids that are absent from Eurypterus, indicates that the Several species of Eurypterus (E. tetragonophthalmus, E. dekayi, rows of acicular scales likely represent a plesiomorphic characteristic E. ornatus Leutze, 1958 and E. hankeni Tetlie, 2006) have a pustular for the more derived Eurypterina. This is supported by some other carapace ornament; however, in all four species the pustules eurypterine species, such as the adelophthalmoid Adelophthalmus are smaller than in Paraeurypterus and Pentlandopterus, and in sievertsi, also having similar rows of scales across the posterior E. tetragonophthalmus the pustules are only found around the margins of the tergites. carapace margin. Most species of Eurypterus also have a row of principal scales across the posterior of the carapace which is absent 6. Phylogenetic analysis of basal Eurypterina in Pentlandopterus, Paraeurypterus and Megalograptus; however, these are absent in E. dekayi, E. ornatus and E. laculatus Kjellesvig- Analysing the matrix as detailed above yielded two most Waering, 1958. The opisthosomal ornament of Paraeurypterus is parsimonious trees with a tree length of 229, an ensemble very similar to that of E. tetragonophthalmus (Wills, 1965 pl. 2 Consistency Index of 0.498, Retention Index of 0.782, and Rescaled Fig. 4) with a row of tightly packed semi-lunate scales across the Consistency Index of 0.389, the strict consensus of which is presented anterior margin, delineating the articulating facet, followed by three here (Fig. 5). The two most parsimonious trees differ solely in the discontinuous rows of loosely spaced scales, and a posterior row of internal topology of the mixopteroid clade, with one tree having larger acicular scales. This type of ornamentation is also seen in Carcinosoma Claypole, 1890b as sister taxon to Megalograptus and Megalograptus; however, Megalograptus and Eurypterus differ from Mixopterus Ruedemann, 1921a and the other with Megalograptus Paraeurypterus in having each acicular scale preceded by a sister to Mixopterus and Carcinosoma. The polytomy of Eurypterus longitudinal row of smaller scales. It seems clear that the similarities species is present in both trees. in ornamentation between the three taxa are not due to convergence, Eurypterids are resolved as a monophyletic clade with Chasma- and the age of Paraeurypterus and Megalograptus, combined with taspidida forming their monophyletic sister-group. Chasmataspidid

Fig. 5. Strict consensus of phylogenetic analysis consisting of 81 characters coded for 45 taxa, resulting in two most parsimonious trees of 229 steps each. The numbers above the branches are Bremer support values while those beneath each branch are jackknife support values after 100,000 repetitions with 25% deletion. Paraeurypterus anatoliensis is highlighted in bold. Author's personal copy

362 J.C. Lamsdell et al. / Gondwana Research 23 (2013) 354–366 monophyly is, in itself, a noteworthy result as they have previously based on Tetlie's unpublished PhD thesis. The topology retrieved in this been suggested not to represent a natural group (Tetlie and Braddy, analysis broadly correlates with that presented by Tetlie (2007a), with 2004). However, in order to test this fully, all the chasmataspidid Mixopteroidea as sister-group to a large clade consisting of species should ideally be included in the analysis with synziphosurines Pterygotoidea, Adelophthalmoidea and the waeringtopterid clade, and xiphosurids as in-group taxa to test whether Chasmataspis Caster within which waeringopterids are sister-group to Adelophthalmoidea and Brooks, 1956 has closer affinities to xiphosurans. Eurypterida is and Pterygotoidea. The analysis differs, however, in the treatment of split into two broad clades: Stylonurina and Eurypterina. Although the basal Eurypterina, including the eurypteroids. only a few Stylonurina were included in the analysis, their monophyly The data for the phylogeny of the basal Eurypterina in Tetlie's was also retrieved in more comprehensive studies of their relationships (2007a) tree predominantly comes from the analysis of Tetlie and by Lamsdell et al. (2010a, 2010b). This is the first time that Cuggy (2007) which united Dolichopteridae and Eurypteridae as a representatives of every major eurypterine clade have been included monophyletic clade, sister-group to the newly named Diploperculata, in a published analysis, and it is interesting to compare the topology with Moselopterus Størmer, 1974 and Onychopterella forming a with the composite tree presented by Tetlie (2007a). Tetlie's composite paraphyletic stem-lineage. The genus Onychopterella was resolved as tree was compiled using the internal topologies of clades retrieved by paraphyletic and ‘Eurypterus’ minor was shown to be phylogenetically Tetlie and Cuggy (2007), Tetlie and Poschmann (2008), and Braddy separate from Eurypterus sensu stricto. Megalograptus was excluded et al. (2008), with the relationships between the major clades inferred from the analysis, however, and in the strict consensus of the eight

Fig. 6. Composite tree showing the relationships of the major eurypterid clades derived from this analysis and that of Lamsdell et al. (2010a, 2010b) with the inferred chasmataspidid sister-group. Solid black bars indicate known ranges, while the black dashed bars show ghost ranges. Grey dashed bars are potential range extensions suggested by fossils in need of further study. The circles indicate single species occurrences; where these are solid grey the taxonomic assignment is certain but the dating is uncertain, while hollow black circles are species that have a confirmed date but are of uncertain taxonomic assignment. Solid black are of definite age and taxonomic assignment. These single species are as follows: 1, Chasmataspidid-like trace (Dunlop et al., 2004); 2, Stylonurella (?) beecheri (Hall, 1884), which is probably a Ctenopterus Clarke and Ruedemann, 1912; 3, Onychopterella (?) pumilus (Savage, 1916), which is probably a Stoermeropterus Lamsdell, 2011; 4, Moselopterus lancmani (Delle, 1937); 5, gotlandicus Kjellesvig-Waering, 1979; 6, Undescribed ‘waeringopterid’ from the St. Peter Formation (Liu et al., 2006); 7, Grossopterus inexpectans (Ruedemann, 1921b); 8, ‘Hughmilleriid’ bearing resemblance to Eysyslopterus Tetlie and Poschmann, 2008 from the Manitoba formations (Young et al., 2007 Fig. 4f); 9, Parahughmilleria maria (Clarke, 1907); 10, Nanahughmilleria clarkei Kjellesvig-Waering, 1964b. Author's personal copy

J.C. Lamsdell et al. / Gondwana Research 23 (2013) 354–366 363 most parsimonious trees, the dolichopterid clade broke down into a of the evolution of a group and responses to global climatic and number of smaller clades that formed a polytomy with Eurypteridae. tectonic changes. One key condition for inferring ghost ranges is Lamsdell et al. (2010a) later added Vinetopterus Poschmann and that the sister taxa compared are both monophyletic, something Tetlie, 2004 and ‘Drepanopterus’ bembycoides Laurie, 1899 to the of particular concern at taxonomic levels higher than species. matrix, resulting in them forming a clade with Moselopterus to which Monophyly of the eurypterid superfamilies is generally well they assigned the name Moselopteridae. supported; exceptions are the eurypteroids, dealt with herein, and Tetlie's (2007a) tree differs in placing Megalograptus above uncertainty over the position of Megalograptus. For the purposes of Onychopterella in the eurypterine stem-lineage and ‘Eurypterus’ minor ghost range inference, Megalograptus has been considered to be a well within the dolichopterid clade. The position of Megalograptus is mixopteroid, probably in a basal position; however, one of the based on a single character, the lack of a modified distal margin of strongest characters uniting Megalograptus with the mixopteroids, the sixth podomere of the swimming leg, but has never been recovered the enlarged spines on appendage III, show some differences in in a phylogenetic analysis. Lamsdell (2011) conducted a more restricted structure that may suggest that they are convergent. Further study analysis of the basal Eurypterina and retrieved a topology that differed of Megalograptus is needed; however, even if it is eventually shown in three ways: Onychopterella monophyletic; Megalograptus forming to be distinct from Mixopteroidea and has closer affinities to a clade with Mixopterus rather than the more basal taxa; and Eurypteridae this will have little effect on the ghost ranges inferred eurypteroids paraphyletic, with Eurypteridae phylogenetically closer under the present topology. to Diploperculata than Dolichopteridae. The current analysis supports After inferring the relationships of the major eurypterid clades, and these results, even with a more inclusive sampling of the dolichopterid comparing their temporal ranges (Fig. 6), it is apparent that the and eurypterid clades. Dolichopteridae is shown to be monophyletic majority have extensive ghost ranges. The majority of these stem from and composed of two clades: one comprising Buffalopterus Kjellesvig- the triploperculate Eurypterina such as moselopterids and dolichopterids. Waering and Heubusch, 1962, Strobilopterus and Syntomopterella The ages of Paraeurypterus, Megalograptus and Orcanopterus suggest that Tetlie, 2007b, the other Dolichopterus Hall, 1859, Ruedemannipterus major cladogenesis of eurypterine groups occurred before the Silurian Kjellesvig-Waering, 1966 and Clarkeipterus Kjellesvig-Waering, 1966. period, during the Katian at the latest. The longest ghost ranges, how- Clarkeipterus has been suggested to be a dolichopterid before (Tetlie ever, are jointly those of Dolichopteridae and the inferred stylonurine et al., 2007b) however this is the first time the genus has been given ancestor of the stylonuroid/kokomopteroid/hibbertopteroid clade, each phylogenetic treatment. ‘Eurypterus’ minor is again distinct from extending for approximately 25 million , while the ghost range for Eurypterus sensu stricto but neither is it a dolichopterid, instead Eurypteridae extends some 22 million years. If, indeed, chasmataspidids resolving as a transitional form between the two clades and elevated are monophyletic and sister group to Eurypterida, then the entire to the new genus Pentlandopterus. Paraeurypterus anatoliensis is also a order has a ghost range of 7 million years given the estimated age of transitional form, appearing morphologically closer to Eurypteridae Chasmataspis (Dunlop et al., 2004). However, if the Cambrian resting but still separated from the clade due to its possession of crescentic trace is indeed assignable to a Chasmataspis-like creature, as sug- lateral eyes with enlarged palpebral lobes and the lack of scales on the gested by Dunlop et al. (2004), then this ghost range would be extended carapace. Neither of these two species are assigned to any taxon higher by a further 33 million years. Alternatively, the trace maker could than the level of genus; instead, they are considered members of a grade represent a form ancestral to both chasmataspidids and eurypterids; incorporating the basal members of the Eurypterina of which the potential support for this stems from the possible identification of a Dolichopteridae and Eurypteridae represent radiations of offshoots metastoma-like plate on one of the traces, the apparent lack of a genital from the main lineage. appendage, and most clearly the possession of six unfused opercula. Where opercula have been identified in chasmataspidids they have 7. Implications for the Ordovician record of eurypterids only been recognized on the three buckler segments (Dunlop, 2002; Tetlie and Braddy, 2004), while having six unfused opercula is the Since Tollerton (2004) recognized that the majority of Ordovician plesiomorphic condition found in xiphosurids. Another potential eurypterids from State (accounting for approximately 75% ghost range extension would be required if some of the eurypterids of Ordovician eurypterid diversity at the time) were either from the St Peter Formation are related to Orcanopterus, as suggested pseudofossils or, in one case, a phyllocarid carapace, Ordovician by Liu et al. (2006), resulting in a further inferred gap of 20 million eurypterids have been considered rare, with the majority of - years for all of the triploperculate Eurypterina. Even without this further level clades originating in the early Silurian. The recent discovery of extension, it is clear that the majority of eurypterid clades must have as yet undescribed eurypterids from the late Ordovician Manitoba existed prior to the late Ordovician extinction pulses during the biotas (Young et al., 2007) and the Middle Ordovician St Peter Hirnantian (Brenchley et al., 2001) and were, therefore, either largely Formation in Iowa (Liu et al., 2006) suggests, however, that unaffected by the mass extinction events or were able to rapidly Ordovician eurypterids are not as rare as has been assumed, and the diversify in their aftermath. discovery of Paraeurypterus serves to strengthen this possibility. Despite the recognition that eurypterids were able to persist through Furthermore, by combining the deeper-level relationships of eu- the end-Ordovician mass extinction, with few long-term detrimental rypterine clades retrieved here with those of Stylonurina recovered effects, it is still unclear where the clade originated geographically, and by Lamsdell et al. (2010a, 2010b), it is possible to estimate ghost to what degree their range included Gondwana prior to its collision ranges of the superfamily-level clades, each of which represent a with Laurussia during the late Devonian and Carboniferous. Tetlie major species diversification within Eurypterida. Ghost ranges are (2007a) considered eurypterids to have originated in Laurentia, with simply the inferred ranges of clades in time based on sister-group Gondwanan occurrences being the result of isolated transoceanic comparison where the sister taxa do not have the same observed dispersal, something generally limited to pterygotoids and some temporal point of origination (see Wills, 1999 Fig. 1) given a mixopteroids. Lamsdell (2011) proposed a method by which the cladogenetic mode of speciation. Furthermore, if the range of the population of Onychopterella augusti – which was not likely to have sister taxon to the initial pair temporally predates this ghost range, been a strong swimmer – could have become established in what is then a ghost range for their ancestor is inferred. Ghost range now South Africa by traversing the sea floor during periods of sea level inference can drastically affect estimations of speciation rates lowstand during the Sandbian or Hirnantian (Saltzman and Young, (Pachut and Anstey, 2007), lineage survival across mass extinctions 2005). Paraeurypterus,phylogeneticallybracketedbydolichopteridsand (Davis et al., 2010), and the nature of lineage diversification (Davis Eurypteridae, was also unlikely to have been a good swimmer and may et al., 2011) and so can have a major impact on our understanding have crossed to Gondwana during theSandbianlowstand.Itisalso Author's personal copy

364 J.C. Lamsdell et al. / Gondwana Research 23 (2013) 354–366 possible that the opposite occurred: periods of lowstand allowed retrieves a topology similar to that of Tetlie (2007a), with a few Gondwanan eurypterids to cross into Laurentia and then undergo an differences: Onychopterella is retrieved as a monophyletic genus and explosive radiation. Currently, the earliest known eurypterid is a Megalograptus is considered to be part of the mixopteroid clade rather stylonurine from the Sandbian of Avalonia, which was at the time located than resolving among the more basal Eurypterina while eurypteroids southwards of Laurentia, and this may, in fact, represent an early are shown not to be a natural group but that Dolichopteridae and stylonurine colonist from Gondwana. This would explain the dearth of Eurypteridae are part of a grade leading to diploperculate Eurypterina Ordovician eurypterids in the well-sampled regions of Europe and with Pentlandopterus and Paraeurypterus being intermediate taxa North America, and would also go some way to explaining why so between the two families. Combining this revised topology of many of the earliest encountered species are relatively advanced eurypterine relationships with that of Stylonurina retrieved by swimming forms – these would have had a greater dispersal ability Lamsdell et al. (2010a, 2010b) permits calculation of ghost ranges than the basal walking forms and so could conceivably appear first in for each of the major clades of Eurypterida and reveals that the the Laurentian and Baltic fossil record if the group did indeed have its majority of eurypterid superfamilies must have originated by the origin in Gondwana. In this scenario, it should still be no surprise that Katian. The occurrence of Onychopterella and Paraeurypterus in the eurypterids are rare in Gondwanan provinces; being a single large Ordovician of Gondwana is puzzling as neither genus was likely to continent Gondwana had comparatively less of the shallow marine have had a spectacular dispersal ability, however it is possible that environments that eurypterids tend to favour, meaning that populations they colonized the continent during periods of sea level lowstand in would likely have been smaller and had a more restricted range. the Sandbian and Hirnantian. One problem with this interpretation Colonizing the shallow seas and island coastlines of Laurentia and Baltica is the implication of a large undocumented record of Ordovician would have led to a period of explosive radiation, resulting in the eurypterids in the well-sampled regions of North America and relatively sudden appearance of multiple clades in the European and Europe. An alternative scenario is proposed whereby eurypterids North American fossil record. The fact that the only eurypterids known originated in Gondwana and radiated out to Laurentia and Baltica in from the Silurian and Devonian of Gondwana are able swimmers the late Ordovician and early Silurian, explaining their sudden suggests the possibility that the Late Ordovician mass extinction did, appearance in the European and North American rock record and indeed, impact the eurypterids, causing them to go extinct on Gondwana shifting the Ordovician record to the historically understudied while the Laurentian species were relatively unaffected, with subsequent Gondwanan continents. It is likely that further study of Gondwanan Gondwanan records representing re-colonization by good dispersers. Ordovician Fossil-Lagerstätten such as the Fezouata formations will The concept that there is an unsampled, early record of reveal more eurypterid species. chelicerates in Gondwana has been mooted previously by Anderson (1996) who suggested that the sudden appearance of weinberginid Acknowledgments synziphosurines during the early Devonian, which retain an extreme number of plesiomorphic morphological features, was due to We thank Sam Ciurca (New York), Peter Van Roy (Ghent University) their radiation from a Gondwanan refuge. The discovery of and Erik Tetlie (Norway) for discussion on the specimen and its possible synziphosurines and xiphosurids (which together probably are not a affinities, Alicia Rosales (University of Kansas) for looking at the potential monophylum – see Lamsdell, 2011) from the and Floian burrows, and Curtis Congreve (University of Kansas) for general Lower and Upper Fezouata Formations of Morocco (Van Roy et al., discussion. Wes Gapp (University of Kansas) assisted with the search 2010) shows that these groups certainly had a Gondwanan presence for some of the more obscure trilobite literature. Úna Farrell (University early in their evolution and their dispersal may have followed a of Kansas) provided invaluable assistance with interpretation of Turkish pattern similar to that proposed here for eurypterids. Eurypterids antique laws and advice on accessioning the specimen. Peter Van Roy and xiphosurans often co-occur throughout the Palaeozoic and provided valuable suggestions and comments during review that greatly eurypterids were probably also present in the Fezouata Formations improved the manuscript. (Van Roy, pers. comm.); if this is the case it would further strengthen the possibility that the group had a Gondwanan origin. Appendix A. Supplementary data

8. Conclusions Supplementary data to this article can be found online at http:// dx.doi.org/10.1016/j.gr.2012.04.006. Paraeurypterus anatoliensis gen. et sp. nov., described from a single specimen, is the tenth eurypterid species known from Ordovician strata and is only the second of that age from Gondwana. Morphologically it References appears intermediate between the eurypteroid families Dolichopteridae Agassiz, J.L.R., 1844. Monographie des poissons fossiles du Vieux Grès Rouge, ou and Eurypteridae, possessing the plesiomorphic conditions of crescentic Système Devonien () des Iles Britanniques et de Russie. eyes with enlarged palpebral lobes and a quadrate carapace with Neufchatel, folio. . 171 pp. Altınlı, L.E., 1963. Explanatory text of the 1:500,000 geological map of Turkey, cizre ornamentation consisting of small pustules but also displaying the sheet. Maden Tetkik ve Arama Enstitüsü (MTA) Publication, Ankara. derived characteristics of genal facets and a row of large acicular scales Anderson, L.I., 1996. Taphonomy and taxonomy of the Palaeozoic . PhD across the posterior of each tergite. These two last characters are thesis, University of Manchester. Eurypterus Megalograptus Anderson, L.I., Selden, P.A., 1997. Opisthosomal fusion and phylogeny of Palaeozoic therefore plesiomorphic for both and ,an Xiphosura. Lethaia 30, 19–31. important recognition as they have previously been used to suggest a Angelin, N.P., 1854. Palaeontologica Scandinavica. Pars 1. Crustacea formationis sister-group relationship between the two taxa. The eurypterine nature transitionis. Fasc. II– Holmiae. Norstedt & Söner, Stockholm. 92 pp., 41 pls. of Paraeurypterus is further supported by prosomal appendage VI having Bozdoğan, N., Ertuğ, K., 1997. Geological evolution and paleogeography of the southeast Anatolia in the Paleozoic. In: Göncüoglu, M.C., Derman, A.S. (Eds.), afourthpodomerethatislongerthanthefifth and appears to expand Paleozoic evolution in NW Gondwana. : Special Publication, 3. Turkish Association distally into a swimming paddle, while a megalograptid affinity can of Petroleum Geologists, Ankara, pp. 39–49. be ruled out because appendage IV is unspecialized, with only Braddy, S.J., Almond, J., 1999. Eurypterid trackways from the Table Mountain Group (Lower Ordovician) of South Africa. Journal of African Earth Sciences 29, 165–177. a single pair of spines on each podomere. The new species most closely Braddy, S.J., Aldridge, R.J., Theron, J.N., 1995. A new eurypterid from the Late Ordovician resembles Pentlandopterus minor,differingonlyinsizeandthe Table Mountain Group, South Africa. Palaeontology 38, 563–581. possession of the acicular opisthosomal scales. Braddy, S.J., Selden, P.A., Doan Nhat, T., 2002. A new carcinosomatid eurypterid from the Upper Silurian of Northern Vietnam. Palaeontology 45, 897–915. Phylogenetic analysis incorporating representatives of each of Braddy, S.J., Poschmann, M., Tetlie, O.E., 2008. Giant claw reveals the largest ever the major eurypterine clades and all triploperculate Eurypterina . Biology Letters 4, 106–109. Author's personal copy

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